Journal of Phytology 2009, 1(5): 342–348 © Journal of Phytology, 2009
ISSN: 2075-6240 Available Online: www.journal-phytology.com REGULAR ARTICLE
YIELD AND WATER USE EFFICIENCY OF BARLEY FODDER PRODUCED UNDER HYDROPONIC SYSTEM IN GCC COUNTRIES USING TERTIARY TREATED SEWAGE EFFLUENTS Asadullah Al Ajmi1, Ahmed Ali Salih1, Isam Kadim2, Yahia Othman1 1Sultan
Qaboos Center for Developed & Soilless Agriculture, Arabian Gulf University, P.O. Box 26671, Manama, Bahrain, 2Department of Animal and Veterinary Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O. Box 34, Al Khoud, postal code 123, Muscat, Sultanate of Oman
SUMMARY In the Gulf Cooperation Council (GCC) Countries, where water is a major limitation in crop production, using alternative water resources such as tertiary treated sewage effluent (TTSE) is one way to produce crops, especially fodders which consume sizeable share of the limited irrigation water. Barley (Hordium vulgare L.) is a popular fodder in the region with good adaptability to wide range of climate and soil. A laboratory experiment was conducted during 2009 using complete randomized design with four replications in order to evaluate yield, water use efficiency (WUE) and quality of barley fodder irrigated with TTSE under hydroponic system. Barley seeds of a commercial grade with good viability (80-85%) were sterilized with 20% sodium hypochlorite solution to control fungal growth. Seeds were sown in stacked trays in a temperature controlled room. Trays were irrigated daily with either tap water (T1), or tap water mixed with TTSE at 20%, 40%, 60%, 80% (T2 to T5) and with TTSE only (T6). Plants were harvested 9 days after sowing. Plant height, green and dry fodder weight, the germination percentages and the amount of water used were recorded. Representative fresh green fodder samples from each treatment were oven-dried at 70oC for 48 hrs and analyzed. Crude protein, Crude fiber CF, acid detergent fiber (ADF), neutral detergent fiber (NDF) and lipid concentrations were determined. Results indicated that germination percent and yield of barley increased as the concentration of TTSE in irrigation water increased, however, the increase in WUE was not significant. Proximate chemical analyses indicated that there was no significant effect of treated sewage effluent on moisture, CF, NDF, ADF, or fat (ether extract) of the barley fodder. It was concluded that barley produced by TTSE maintained all its fodder quality and that it can be produced commercially for feeding livestock. Keywords: Treated sewage effluent, fodder barley, hydroponic systems, water use efficiency. A. Al Ajmi et al. Yield And Water Use Efficiency of Barley Fodder Produced Under Hydroponic System In GCC Countries Using Tertiary Treated Sewage Effluents. J Phytol 1 (2009) 342-348 *Corresponding Author, Email:
[email protected]
A. Al Ajmi et al./J Phytol 1 (2009) 342-348
1. Introduction The Gulf Cooperation Council (GCC) countries are located in a desert region, which is characterized by high temperatures, high evaporation rates and low and erratic rainfall. Irrigated agriculture is by far the largest water user with around 78% on average of the total water use in all GCC countries [1]. Most agricultural water (85%) is groundwater, which is largely non-renewable [2]. The amount of abstraction of ground water is by far greater than the recharge and aquifer levels are rapidly declining and ground water is increasing in salinity by intrusion of sea water [1]. There is a sharp decline in availability of underground water to be used for irrigation in the GCC region. Water use efficiency (WUE) is generally low under field conditions in the region [3]. Several strategies have been suggested to improve the productivity of water, among which is better management of the water resource [4]. Hydroponics growing techniques improve WUE by restricting water loss [5]. This technique can be used to produce fodder in very short periods (7-10 days) and it has been proven to be efficient both financially and environmentally [6]. It is estimated that with this technique, the costs of agricultural inputs are at least 10 times lower than under field conditions [7]. High water use efficiency is, however, a major advantage of this technique which saves about 95-97% of used water in comparison to conventional agriculture with small piece of land [3]. Green forage production in the GCC countries is limited by its high water consumption and less water use efficiency per unit of green forage produced (130 liters per kg green fodder) [8]. The limited availability of traditional water resources necessitates the use of non-traditional resources in agriculture among
which is treated sewage water. The current primary use of treated wastewater in GCC countries is for municipal landscaping while a significant volume is lost to the sea even after it is treated to the secondary level [1]. Currently, about 60% of sewage effluent in GCC countries is treated but its use in agriculture accounts for only 2% of the total amount of water used in crop production [1]. The present study aimed at studying the potential of utilizing tertiary treated sewage effluent (TTSE) to produce fresh and safe barley fodder using hydroponics system. This work is presented in two papers. The current paper investigates yield and WUE of the hydroponically produced barley sprouts using TTSE. Issues related to chemical compositions and heavy metals residues in plant tissues are covered in the subsequent paper.
2. Materials and methods The experiment was conducted in a temperature controlled room (23±2O C, RH 70 ±5%) at Sultan Qaboos Center for Developed and Soilless Agriculture, Arabian Gulf University, Bahrain, in a hydroponic system. Clean seeds of barley (Hordeum vulgare L.) of a commercial grade with good viability (80-85%) were used. Seeds were sterilized by soaking for 30 minutes in 20% sodium hypochlorite solution. Seeds were then washed and soaked in distilled water for 14 hours. Eighty grams of seeds were sown per tray (dimensions 40 cm × 43 cm × 6 cm). This is equivalent to seed rate of 4.65 kg/m2. Holes were made at the bottom of the plastic trays to freely drain excess irrigation water. The trays were stacked on shelves in a randomized complete block design with four replicates. The trays were 343
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covered with plastic cover to prevent seed drying. Trays were irrigated daily with either tap water (T1, control), or tap water mixed with tertiary treated sewage effluent (TTSE) at 20%, 40%, 60%, 80% (T2 to T5) and with TTSE only (T6). The experiment was terminated 9 days after sowing by harvesting the plants. The data collected included plant height, green and dry fodder weight, the amount of non-germinated seeds and the amount of water used. Water use efficiency was computed as amount of dry matter produced/unit of water used. The proximate chemical composition of dry fodder samples was determined according to standard methods of AOAC (2000). Dry matter (DM) was determined by drying in an oven for 24 hours at 80ºC (method 934.01). Crude protein (CP) was determined using a Foss Tecator Kjeltec 2300 Nitrogen / Protein Analyzer (method 976.05). Fat (ether extract EE) was determined by Soxhlet extraction of the dry sample, using petroleum ether (method 920.39). Ash content was determined by ashing samples in a muffle furnace at 500ºC for 24 hr (method 942.05). Acid detergent fibre (ADF) was determined using cetyl trimethyl ammonium bromide (CTAB) and 1N H2SO4 [9]. Neutral detergent fiber (NDF) was determined using sodium sulphite and sodium lauryl sulphates [10]. Crude fiber was analyzed by FOSS Fibertec system according to Weende, van Soest method. Data were statistically analyzed using analyses of variance (ANOVA) by MSTAT Statistical Package [11]. Probabilities of significance among treatments and interaction and LSDs (P>0.05) were used to compare means within and among treatments.
3. Results and discussion Irrigation water quality The analysis of irrigation water used for the various treatments is reported in Table 1. The salinity of irrigation water ranged between 0.34 dS/m (tap water) and 4.08 dS/m (TTSE). The pH values ranged from 7.28 for the tap water to 7.94 for the TTSE. Nitrogen content increased from 100 ppm in tap water (control, T1) to 290 ppm in pure TTSE (T6). As expected, the levels of EC, pH and total nitrogen in various treatments (T2T5) have progressively increased with increasing the proportion of TTSE in the irrigation water (Tables 1). Table 1. EC, pH and nitrogen content of irrigation water used in the various treatments. Treatments
1
T1
TTSE in irrigation water (% ) Tap water only
EC (dS/m) 0.34
pH 7.28
Total N (ppm) 10
T2
20
1.1
7.33
80
T3
40
1.9
7.37
160
T4
60
3.07
7.42
180
T5
80
3.48
7.72
220
T6
TTSE only
4.08
7.94
290
It has been reported that hydroponically grown barley can tolerate EC values above 6 dS/m without any impact on seed germination or crop yield [12]. N concentration in TTSE is adequate to maintain good barley growth according to Benton [13]. Fodder yield Table 2 shows total crop yields (on green and dry weight basis) and crop heights at harvest. Average green forage yield ranged from less than 90 tones/ha with tap water to around 130 tones/ha with TTSE (T6). This is equivalent to 50% increase in fodder production. This increase in yield may be attributed to the high nitrogen content in TTSE.
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Table 2; Fresh yield, dry matter, plant height and ratio of green forage to seeds rate of barley in the various treatments. T1
Green forage ton/ha 86.1c
Dry matter ton/ha 19.46a
Crop heights at harvest (cm) 15.3a
Green forage to seeds rate 1.85c
T2
81.6c
16.32ab
15.1a
1.75c
T3
105.6abc
21.65abc
16.0a
2.27abc
T4
103.0bc
20.91bc
14.9a
2.22bc
T5
112.3ab
23.02c
17.1a
2.42ab
T6
128.3a
24.63c
18.1a
2.76a
Treatments
1
Means followed by the same letter in a column are not significantly different at P
